The present invention relates to a process and an apparatus for detecting the presence of defects in monocrystalline structures.
The process which is at present most widely employed for effecting a quality control on monocrystalline structures is the LAUE process. Processes are also known employing a macro and micrographic observation.
The LAUE process on the other hand is a long and costly process requiring a preparation and use of point "shots" on the object to be examined, these "shots" covering only a very small area of about 1 sq. mm and consequently requiring to be multiplied a large number of times at many different angles, without however covering the whole of the surface area of the object, so that there subsists a wide margin of uncertainty while only the crystallographic orientation is given.
The applicant has found that it is possible to determine the crystallographic quality of monocrystalline structures by a rational exploitation of diagrams composed of Kikuchi pseudo-lines. However, the known present process for obtaining Kikuchi pseudo-lines consists in bombarding a monocrystalline structure placed in a vacuum with a beam of electrons, these lines appearing in the electronic microscope. This vacuum pressure process consequently cannot be practically used with objects of large dimensions having a monocrystalline structure, such as for example turbine blades.